1. Field of the Invention
The present invention relates to automatic gear-shifting bicycles and more particularly, to an automatic gear-shifting bicycle with optimal shift timing.
2. Description of the Related Art
In regular automatic gear-shifting bicycles, the shift timing is normally determined subject to the speed of the bicycle and the speed of the pedal. At the present time, no any shift timing determination technology is based on pedaling foot angle. If a rider of an automatic gear-shifting bicycle shifts the gears when pedaling the pedals heavily, shifting of the gear ratio of the derailleur will be unstable, affecting bicycle riding comfort. Therefore, when shifting the gears while pedaling the pedals lightly, the derailleur will be operated smoothly, enhancing bicycle riding comfort.
However, shifting the gears of an automatic gear-shifting bicycle must be performed during forward pedaling, and therefore, determining shift timing subject to the rider's pedaling status must consider the pedaling direction, i.e., pedaling direction must be simultaneously taken into account.
WO 2009036623 discloses a power control device for electric bike, which uses a Hall sensor for sensing, determining whether or not the electric bike is moving forward. In the specification, FIG. 2 and FIG. 3 respectively illustrate the waveforms sensed by the Hall sensor during forward rotation and backward rotation.
CN 101412427 discloses a backward pedaling detection circuit for an e-bike motor driver, comprises a charging/discharging circuit for charging and discharging the external capacitor to meet the threshold voltage required by the hysteresis comparator, based on the input from the Hall sensor, avoiding false triggering of motor. This invention also discloses a Hall sensor to detect forward/backward rotation.